1,1-Dichloroethane → 1-(4-Chloro-phenyl)-3-[4-hydroxy-3-(2-methyl-2H-pyrazol-3-yl)-phenyl]-urea

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Reaction Steps

To a mixture of 1-[3-(2-methyl-2H-pyrazol-3-yl)-4-methoxy-phenyl]-3-(4-chloro-phenyl)-urea (6.35 g, 17.8 mmol) and dichloroethane (500 mL), tribromoborane (10 mL, 106 mmol) was added. The mixture was allowed to warm to room temperature. After stirring over the weekend, the mixture was cooled in an ice bath and a mixture of ice cold ammonium hydroxide and water (ca. 100 mL) was added slowly. The mixture was transferred into a separatory funnel and extracted with methylene chloride and water. Solid in the water phase was filtered off and washed with water to give 1-[3-(2-methyl-2H-pyrazol-3-yl)-4-hydroxy-phenyl]-3-(4-chloro-phenyl)-urea as a white solid (4.92 g, 90% pure, 12.7 mmol, 71%). Combined organic phases were dried over MgSO4, filtered, and concentrated to afford additional 1-[3-(2-methyl-2H-pyrazol-3-yl)-4-hydroxy-phenyl]-3-(4-chloro-phenyl)-urea as a white solid (1.71 g, 4.99 mmol, 28%). Overall yield: 99%. LCMS m/z (%)=343.1 (M+H). 1H NMR (400 MHz, CDCl3) δ: 9.60 (br s, 1H), 8.78 (s, 1H), 8.53 (s, 1H), 7.48-7.42 (m, 3H), 7.32-7.27 (m, 4H), 6.91-6.89 (m, 1H), 6.21 (d, J=1.8 Hz, 1H), 3.68 (s, 3H).

Provenance & Evidence